Method of detecting defects and composition therefor

ABSTRACT

A method of detecting defects in substrates comprising the steps of applying to a substrate, a composition comprising a fugitive tint and a solvent mixture containing at least two solvents of differing polarity which are substantially immiscible under certain conditions, and permitting said composition to undergo phase separation whereby the tint migrates with one of the solvents to a portion of the substrate to facilitate visual inspection of the substrate. Also, a detecting composition.

United States Patent [1 Farmer et al.

[ 1 Dec. 30, 1975 [54] METHOD OF DETECTING DEFECTS AND COMPOSITION THEREFOR [73] Assignee: Deering Milliken Research Corporation, Spartanburg, S.C.

[22] Filed: May 21, 1973 [21] Appl. No.: 361,994

[52] US. Cl. 8/164; 8/174; 8/94 3,663,262 5/1972 Cogan 8/164 3,706,525 12/1972 Blackwell et al. 8/93 3,758,272 9/1973 Datye 8/173 3,819,324 6/1974 Bino 8/164 Primary ExaminerDonald Levy Attorney, Agent, or Firm -ld. William Petry; Arthur L. Urban [57] ABSTRACT A method of detecting defects in substrates comprising the steps of applying to a substrate, a composition comprising a fugitive tint and a solvent mixture containing at least two solvents of differing polarity which are substantially immiscible under certain conditions, and permitting said composition to undergo phase separation whereby the tint migrates with one of the solvents to a portion of the substrate to facilitate visual inspection of the substrate. Also, a detecting composition.

23 Claims, No Drawings METHOD OF DETECTING DEFECTS AND COMPOSITION THEREFOR A dependable, efficient system for a preliminary test to insure uniform dyeing has long been needed by the textile industry. Likewise, there has been a need for a means to detect at an early stage physical defects in fabrics that are continuous and/or repetitive due to mechanical malfunctions of the machines, varying tensions on the ends of yarn, and the like.

The problem of fabric defect detection is further compounded by the use of textured synthetic yarns which possess different dye affinity depending upon the type of yarn, the number of filaments or fibers in yarn bundle, the heat history of the yarn during texturing, the particular texturing process utilized, and similar factors. In the respective texturing processes, there are certain variables that introduce different dye characteristics to yarns produced by the particular process. For example, where the yarn is heated to a plastic state and a twist is set therein as in a false twist process, different heat histories of the yarns so processed can well affect the dyeing of the yarn. Likewise, in an edge crimping process where the yarn is passed over an edge, variations in the sharpness of the edge may create different characteristics in the yarn which may affect the dyeing of the yarn.

Another critical areais in the knitting steps per se. For example, with double knit machines having a large number of separate feed yarns, the tension on each end must be controlled to knit a uniform fabric. Nonuniform tension on one or several of the ends around the machine will adversely affect the dye receptivity of the particular ends of yarn and produce streaks in the finished, dyed fabric. These streak characteristics are generally referred to as barre. If barre is not detected until the goods are dyed, second quality goods are produced which must be segregated and sold at a lesser price. It is advantageous to check a fabric prior to the dyeing of the fabric, so those fabrics which indicate barre may be segregated from other fabrics and dyed with low energy or less critical color shades to produce first quality fabrics.

An article in Modern Knitting Management, February 1973, pp. l8-22, sets forth the advantages of dye testing fabrics containing textured yarns to permit segregation of the fabrics into lots prior to permanent dyeing of the whole piece of goods. Thee article states that two techniques are available for group segregation of textured yarns. The first of these is the dyeing of sample panels knitted from the yarn according to conventional dyeing techniques. A second approach mentioned in the article is a reflectometer technique.

A polyester fiber identification system has been proposed in Knitting Industry, November 1972, page 44. ln this system, colorants are applied to a fabric or group of fibers in a two-step operation with a preparation solution being brushed onto the fabric and after thirty seconds a special blue colorant is sprayed onto the fabric. Heat then is applied to hasten development. This technique is said to allow identification or separation of basic dyeable polyester from regular polyester.

The present invention provides a simple and quick method for'identifying defects in substrates. Further, the invention provides a single-step method which permits the visual observation of defects of a physical, chemical and/or optical nature in textiles without cutting samples and/or machine stoppage. This results in fewer seconds and increased production rates. The present invention also provides a technique for detecting the probability and degree of barre in textile fabrics before the fabrics are finished. Moreover, the invention provides a novel composition for detecting textile defects.

The method of the present invention generally comprises the steps of applying a composition comprising a fugitive tint and a solvent mixture containing at least two solvents of differing polarity which are substantially immiscible under certain conditions, and permitting said composition to undergo phase separation whereby the tint migrates with one of the solvents and is affixed or diffused to a portion of the substrate to facilitate visual inspection of the substrate.

The term fugitive tint as used herein refers to any dyestuff, colorant, pigment, UV absorber and the like that may be applied to textiles and subsequently removed therefrom by washing or scouring without retaining color or adversely affecting dyeability. Suiitable tints are polyethyleneoxy tints such as those marketed by Milliken Chemical Division of Magnolia Industries,

Inc., lnman, South Carolina, under the trademark VERSATINT. Preferred. polyethyleneoxy tints have the following formula:

wherein R is a dyestuff radical, n is at least 15, x is from 1 to 6, and the product of n times x is at least 30, preferably between 50 and 200, and more preferably between about and 150. Fugitive tints described in US. Pat. No. 3,157,633 to Kuhn are particularly useful. The tint color is selected to provide good contrast with the substrate. Blue and green tints are useful with undyed textiles.

In the present invention, after the detecting composition is applied to a textile, the composition changes character and one of the components thereof preferentially migrates to a particular portion of the textile, thus facilitating visual inspection of the textile in search of chemical, physical and/or optical defects therein.

The substrate treated according to the method of the present invention may be any surface that will accept components of the treating composition unevenly due to physical or chemical characteristics of the substrate, for example, textiles, plastics, etc. Preferably, the substrate is a textile such as a woven, knitted, or nonwoven fabric, silver, batt, yarn or the like. Further, the substrate may contain natural or synthetic fibers or filaments or mixtures thereof. Particularly suitable are blends of two different types of polyester fibers.

The composition and method of the invention may be used to detect a wide variety of chemical, physical and/or optical defects including the following typical examples: barre, misdrawn ends, needle marks, low bulk ends, off-quality denierv ends, yarn mixes, and the like. The composition of the present invention may be applied to mixtures of basic dyeable polyester and regular dyeable polyester to visually observe and segregate the basic or cationic dyeable polyester from the regular polyester. Thus, if a particular pattern is intended to include cationic dyeable polyester in one portion and regular polyester in another portion, the correctness of the design may be verified quickly and accurately without removing a sample of the goods or disrupting operation of the machine producing the goods. Moreover, this can be accomplished without adversely affecting the finished goods.

Also, in the knitting of fabrics, a plurality of yarns is simultaneously fed to the knitting needles from separate locations around the periphery of the machine. Yarn tension must be closely controlled to produce first quality fabric and each end must be controlled individually. if proper tension control on one or more of the ends of yarn is lost, the affected ends of yarn will be knitted into the fabric under off-target tension conditions. After dyeing the fabric, the off-target tensioned ends of yarn may appear as different color streaks in the fabric.

Additionally, needles used to knit fabric are very fragile and subject to damage, which can produce fab ric defects such as needle marks that appear in the dyed fabric. Visual observation of such defects shortly after damage to the needle permits replacement of the needle before large amounts of off-quality fabric have been produced.

During the production and texturing of certain synthetic yarns, several variables are encountered that can change the dyeability characteristics of the yarn. One variable is the heat history of the yarn. During the texturing, the yarn is subjected to a predetermined amount of heat. Apparatus malfunction, improperly set apparatus and the like may cause different ends of yarn to be subjected to a different level of heating, which will influence the dyeing characteristics of the individual ends. Where two differently processed ends of yarn are utilized in a single fabric to be dyed with a critical dye shade, differential dyeing may be visually apparent in the finished goods. Detection of these different dyeing characteristics prior to actual dyeing permits segregation of the fabric into lots to be dyed with less critical shades. Thus, the fabric, though a potential off-quality fabric, is retained as a first quality fabric when dyed with a less critical shade. In this regard, low energy dyestuffs are generally less critical than high energy dyestuffs.

Numerous other defects may likewise be sought when using the composition and process of the present invention. For example, knitting machines are set up to knit a particular pattern into a fabric. However, during the setting up of the machine, one or more ends may be misaligned to create an incorrect pattern in the fabric. Once the knitting machine is put into production, it is difficult to detect an imperfection in the pattern being knitted. However, by following the present invention, the correctness of the pattern or presence of defects may be ascertained rapidly as the fabric is being knitted without stopping the machine. The capability of defect detection without machine stoppage is especially important in knitting operations which produce a defect at each machine stop.

Further, since different fiber producers utilize different processes for the production and texturing of yarns, the yarns from the different producers may possess different dyeing characteristics. The present invention may be utilized to detect the presence of such different yarns. 1n the same way, differences in the number of filaments in a yarn bundle as well as numerous other potential errors may be detected. While the present invention is particularly useful on finished textiles such as knitted, woven and nonwoven fabrics, the invention also may be utilized in fiber and yarn preparation such as with webs, slivers, warp beams and the like.

The defect detecting composition of the present invention advantageously is made up of a small quantity of a fugitive tint anad a suitable solvent mixture, al-

though the tint concentration may vary from about 0.01% up to 25% or more by weight. Advantageously, with polyethyleneoxy fugitive tints, the concentration is between about 0.1% and 5%. The solvents are of differing polarity and are substantially immiscible in certain proportions or under certain conditions. The tint preferably is soluble in at least one of the solvents and insoluble in at least another of the solvents. Either polar or nonpolar type solvents may dissolve the tint, depending upon the particular tint and solvents employed, with the tint being insoluble in the opposite type.

While a solvent mixture is always present at the time of application onto the substrate, the preparation of the detecting composition varies. With certain polar and nonpolar solvents which are soluble in each other, the tint enters the solution via the solvent in which it is soluble. Often, the solvents form a solution only in a particular range of ratios and not in other proportions. Such solvent mixtures are desirable for the purposes of the present invention since, after application of the composition to the substrate, one of the solvents evaporates more rapidly than the other to create an imbalance in the ratio and separation of the solvents. Alternatively, two solvents of differing but similar type polarity that are immiscible in each other may be employed, e.g., a mixture of a highly polar solvent and a solvent of low polarity. In this situation, a third solvent is added in which both of the first two solvents are miscible and a solution is formed. After application, evaporation of the third solvent brings about a phase separation of the first two solvents. Virtually any polar and nonpolar solvents may be utilized according to the present invention, with the particular solvent selection being dependent upon solubility of the tint, and solubility in each other or a third or fourth solvent. Selection of the solvents also may be based on flammability and- /or toxicity requirements. In some cases, the solvents may be selected to provide differing UV absorbing characteristics.

With the evaporation of one of the solvents, phase separation occurs on the substrate very quickly after application, with the tint following the particular solvent in which it is soluble or has an affinity. Generally, the phase separation occurs within about 5 to 10 seconds after application under ambient conditions, which permits inspection without machine stoppage. With some of the solvent mixtures, contrast is retained for relatively long periods while with other mixtures, contrast is lost more quickly. In any case, visual inspection is preferably made while a sharp contrast is present.

The present invention will be more fully understood by reference to the following examples, which are intended to be illustrative without limiting the scope of the invention. Unless otherwise specified, amounts are listed as weight parts.

EXAMPLES 1-27 Defect detection solutions are prepared by mixing solvent and fugitive tent components as listed below in Table 1. In each example, the composition is applied to a knitted textile fabric containing both cationicdyeable polyester and regular polyester filaments. The composition is applied by pouring same over a portion of the knitted fabric until there is apparent saturation of the fabric at the contacted area. After about 5 to 60 seconds, portions of the solvents evaporate, phase separation occurs and the fugitive tint migrates together with 5 6 its solvent to the cationic-d cable 01 es com em y g p y P EXAMPLE 41 The tinted polyester filaments are readily visible due Two parts KPD-2 Green concentrated Easy-Red to the blue or green hue while the regular dyeable tint, adyestuff fugitive tint manufactured by Industries polyester filaments remain virtually untinted. Research, Inc., Scranton, Pennsylvania.

TABLE I VERSATINT EXAMPLE NO. PERCHLOROETHYL. METHA- DlOXANE Blue 64 Green LF ENE NOL VERSATINT is the registered trademark for a polyethyleneoxy fugitive tint produced by Milliken Chemical Division, Magnolia Industries, lnc., lnman, South Carolina.

EXAMPLES 28-40 EXAMPLE 42 The following compositions are prepared and like- Two parts of tinting Yellow L, a p-nitrophenol salt wise poured over a knitted polyester fabric as described fugitive tint manufactured by Milliken Chemical Diviin Examples l-27. The compositions listed in Table II 40 sion of Magnolia Industries, Inc., Inman, South Caroexhibit a green or blue color and likewise show good lina. pattern and fiber location within 5 to 60 seconds.

TABLE II VERSATlNT Ethylene Per- Glycol chlo- 1 Methyl,l,l- Stodlso- Monorolene For- Tridard pro- Green Blue Ex. methyl ethy- Chlormachloro- Sol- Methpa- Ace- Ben- LF 64 No. Ether lene ide mide Water ethane vent anol nol tone zene 65% 28 4 20 20 l 29 ll 20 20 l 30 ll 38 20 l 3] ll 38 30 l 32 5 40 20 l 33 I6 38 30 l 34 ll 38 3O 5 35 ll 38 2O 2 36 ll 20 IO 40 20 4 37 2O 5 30 4O 4 38 40 5 5 30 1.5 39 20 50 2O 4 40 20 50 20 25 2 V V I In order to evaluate other fug1t1 e tints, a IOUS com EXAMPLE 43 mercially available tints are incorporated in a standard solvent solution comprising 33 parts of perchloroethyl- 65 0.2 parts of Nylon Canary Fugitive Tint dissolved in ene, ll parts of ethylene glycol monomethyl ether and one part of methyl alcohol, an aqueous fugitive tint 20 parts of methylene chloride. These solutions are set manufactured by US. Testing Company, Hoboken, forth in the following examples: New Jersey.

EXAMPLE 44 0.2 parts ofI Nylon Orange dissolved in one part of methyl alcohol, an aqueous fugitive tintmanufactured by US. Testing Company, Hoboken, New Jersey.

EXAMPLE 45 Four parts of Green V tint, a complex of acid dyestuffs and polyvinyl pyriolidone manufactured by Chemurgy Products, Inc., Greenville, South Carolina.

As can be seen from the above, numerous and sundry types of fugitive tints may be utilized in the identification compositions of the present invention. In each of Examples 41-45, the fugitive tint composition provides excellent visual identification of the fiber groups and shows excellent pattern identification.

Utilizing the compositions set forth above, additional tests are run on cotton jersey knits, knit fabrics with polyester filament yarns manufactured by different producers, mixtures of polyester fibers in sliver form, warp knitted fabrics from polyester spun yarns and the like. Visual observation of the fabrics prior to testing shows little or no evidence of differences in any of the textile goods. After pouring the detection composition onto the fabrics, the tint immediately begins to develop coincident with evaporation of the solvents whereupon the patterns in all of the goods become clearly visible. The yarns of different producers exhibit different shades; the slivers with different numbers of yarns exhibit different shades; and cationic dyeable polyester is clearly distinguishable from regular dyeable polyester. The shade differences between certain of the ends of yarn are only slight but are readily observable.

In plant tests, also, the present composition and process permit particular ends of yarn to be traced back to their sources to identify damaged needles, incorrect tension, different heat histories for the yarns, different numbers of filaments in yarn bundles, different producers, and the like. In each of these cases, the yarns are later scoured and permanently dyed according to conventional production techniques. In each case where a defect or faulty yarn is observed by the detection tests according to the present invention, the dyed fabric shows a like imperfection. In some cases, however, the imperfections noted after dyeing are not as pointed as observed with the method according to the present invention.

Having described the present invention in detail, it is obvious that one skilled in the art will be able to make variations and modifications thereto without departing from the scope of the invention. For example, the concentration of the fugitive tint may be varied and other materials which do not adversely affect the functioning of the composition may be added. Likewise, the substrate may be subjected to sequential treatments with the composition, if desired. Accordingly, the scope of the present invention should be determined only by the claims appended hereto.

That which is claimed is:

1. A method of detecting defects in fabrics comprising the steps of:

a. applying to a fabric, a composition comprising a fugitive polyethyleneoxy modified dyestuff and a solvent mixture containing at least two miscible solvents of differing polarity which are substantially immiscible when exposed to the atmosphere in thin films, and

8 b. permitting said composition to undergo phase separation on said fabric whereby the tint migrates with one of the solvents to a portion of the fabric to facilitate visual'inspection of the fabric.

2. The method as defined in claim 1 wherein said fugitive tint is soluble in one of said solvents and substantially insoluble in the other of said solvents.

3. The method as defined in Claim 1 wherein said polyethyleneoxy fugitive tint has the formula z z l, wherein R is a dyestuff radical, n is at least 15, x is from 1 to 6, and the product of n times x is at least 30.

4. The method as defined in claim 1 wherein said polyethyleneoxy fugitive tint has the formula wherein R is an organic dyestuff radical, R is a member selected from the group consisting of hydrogen, lower alkyl, aryl and aralkyl containing from 6 to 12 carbon-atoms, and (CH CH O),, H, n is at least 15, x is from 1 to 6, and the product of n times x is at least 30.

5. The method as defined in claim 1 wherein one of said solvents is a polar solvent and a second solvent is a non-polar solvent.

6. The method as defined in claim 1 wherein the solvent mixture comprises perchloroethylene and methanol.

7. The method as defined in claim 6 wherein the solvent mixture further comprises dioxane.

8. The method as defined in claim 1 wherein the solvent mixture comprises 1,1 ,1-trichloroethane, formamide, methanol and methylene chloride.

9. The method as defined in claim 1 wherein the solvent mixture comprises perchloroethylene, methylene chloride and'ethylene glycol monomethyl ether.

10. The method as defined in claim 1 wherein said composition includes water.

11. The method as defined in claim 1 wherein the solvent phase separation and tint migration takes place at ambient temperature.

12. The method as defined in claim 1 wherein the substrate is a textile.

13. The method as defined in claim 1 wherein the substrate is a textile fabric including two different types of polyester fibers.

14. A detecting composition comprising a fugitive polyethyleneoxy modified dyestuff and a solvent mixture containing at least two miscible solvents of differing polarity which are substantially immiscible when exposed to the atmosphere in thin films whereby the tint migrates with one of the solvents.

15. The composition as defined in claim 14 wherein said fugitive tint is soluble in one of said solvents and substantially insoluble in the other of said solvents.

16. The composition as defined in claim 14 wherein said polyethyleneoxy fugitive tint has the formula 2 2 )n ]-t wherein R is a'dyestuff radical, n is at least 15, x is from 1 to 6, and the product of n times x is at least 30.

17. The composition as defined in claim 14 wherein said polyethyleneoxy fugitive tint has the formula wherein R is an organic dyestuff radical, R is a member selected from the group consisting of hydrogen, lower alkyl, aryl and aralkyl containing from 6 to 12 carbon atoms, and -(CH CH,. O), H, n is at least 15, x is from 1 to 6, and the product of n timesx is at least 30.

18. The composition as defined in claim 14 wherein one of said solvents is a polar solvent and a second solvent is a non-polar solvent.

said composition includes water.

UNITED STATES PATENT OFFICE CERTIFICATE OF CQRRECTION Patent No. 3, 929,406 Dated December 30, 1975 Inventor(s) Larry B. Farmer et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 15, the words "in yarn" should read --in a yarn-- Column 1, line 49, the word Thee should read --The-- Column 2, line 21, the word "Suiitable" should read --Suitable-- Column 3, line 68, the Word anad" should read --and- Column 4, line 60, the word "tent should read --tint- Signed and ficaled this eleventh Of May 1976 [SEAL] Atresr:

RUTH C. MASON C. MARSHALL DANN If/76W (unmzissiuncr uflalenls and Trademark; 

1. A METHOD OF DETECTING DEFECTS IN FABRICS COMPRISING THE STEPS OF: A. APPLYING TO A FABRIC, A COMPOSITION COMPRISING A FUGITIVE POLYETHYLENEOXY MODIFIED DYESTUFF AND A SOLVENT MIXTURE CONTAINING AT LEAST TWO MISCIBLE SOLVENTS OF DIFFERING POLARITY WHICH ARE SUBSTANTIALLY IMMISCIBLE WHEN EXPOSED TO THE ATMOSPHERE IN THIN FILMS, AND B. PERMITTING SAID COMPOSITION TO UNDERGO PHASE SEPARATION ON SAID FABRIC WHEREBY THE TINT MIGRATES WITH ONE OF THE SOLVENTS TO A PORTION OF THE FABRIC TO FACILITATE VISUAL INSPECTION OF THE FABRIC.
 2. The method as defined in claim 1 wherein said fugitive tint is soluble in one of said solvents and substantially insoluble in the other of said solvents.
 3. The method as defined in Claim 1 wherein said polyethyleneoxy fugitive tint has the formula R((CH2CH2O)nH)x wherein R is a dyestuff radical, n is at least 15, x is from 1 to 6, and the product of n times x is at least
 30. 4. The method as defined in claim 1 wherein said polyethyleneoxy fugitive tint has the formula
 5. The method as defined in claim 1 wherein one of said solvents is a polar solvent and a second solvent is a non-polar solvent.
 6. The method as defined in claim 1 wherein the solvent mixture comprises perchloroethylene and methanol.
 7. The method as defined in claim 6 wherein the solvent mixture further comprises dioxane.
 8. The method as defined in claim 1 wherein the solvent mixture comprises 1,1,1-trichloroethane, formamide, methanol and methylene chloride.
 9. The method as defined in claim 1 wherein the solvent mixture comprises perchloroethylene, methylene chloride and ethylene glycol monomethyl ether.
 10. The method as defined in claim 1 wherein said composition includes water.
 11. The method as defined in claim 1 wherein the solvent phase separation and tint migration takes place at ambient temperature.
 12. The method as defined in claim 1 wherein the substrate is a textile.
 13. The method as defined in claim 1 wherein the substrate is a textile fabric including two different types of polyester fibers.
 14. A detecting composition comprising a fugitive polyethyleneoxy modified dyestuff and a solvent mixture containing at least two miscible solvents of differing polarity which are substantially immiscible when exposed to the atmosphere in thin films whereby the tint migrates with one of the solvents.
 15. The composition as defined in claim 14 wherein said fugitive tint is soluble in one of said solvents and substantially insoluble in the other of said solvents.
 16. The composition as defined in claim 14 wherein said polyethyleneoxy fugitive tint has the formula R((CH2CH2O)nH)x wherein R is a dyestuff radical, n is at least 15, x is from 1 to 6, and the product of n times x is at least
 30. 17. The composition as defined in claim 14 wherein said polyethyleneoxy fugitive tint has the formula
 18. The composition as defined in claim 14 wherein one of said solvents is a polar solvent and a second solvent is a non-polar solvent.
 19. The composition as defined in claim 14 wherein the solvent mixture comprises perchloroethylene and methanol.
 20. The composition as defined in claim 19 wherein the solvent mixture further comprises dioxane.
 21. The composition as defined in claim 14 wherein the solvent mixture comprises 1,1,1-trichloroethane, formamide, methanol and methylene chloride.
 22. The composition as defined in claim 14 wherein the solvent mixture comprises perchloroethylene, methylene chloride and ethylene glycol monomethyl ether.
 23. The composition as defined in claim 14 wherein said composition includes water. 